bug#17534: AppleAntiAliasingThreshold default doesn't seem to work

[David Logie]

This bug seems to have been introduced in r114295. A build from r114294
does not have the issue while a build from r114296 does.

Looking at the Mac port, I *think* a call to
`macfont_update_antialias_threshold()` has been missed somewhere.

I managed to cobble together a patch that works for me (see attached)
but I'm sure a more correct solution exists.

17534-antialias.patch
Description: Text document